1. Technical Field
The present inventive concept relates to a nonvolatile memory device using a variable resistive element.
2. Discussion of the Related Art
Nonvolatile memory device types include, for example, phase change random access memory (PRAM), which utilizes a phase-change material such as a chalcogenide alloy that can be switched between two states, resistance random access memory (RRAM), which takes advantage of controllable resistance changes in metal oxides, and magnetic random access memory (MRAM), which utilizes magnetic tunnel junction (MTJ) thin films whose resistance changes according to a magnetization state of a ferromagnetic substance. A resistance value is maintained in these devices even when no current or voltage is supplied, thereby demonstrating nonvolatile memory characteristics.
For example, the phase-change material of a PRAM becomes crystalline or amorphous as it is cooled after being heated. The phase-change material has low resistance in the crystalline state and high resistance in the amorphous state. Therefore, the crystalline state may be defined as set data or data 0, and the amorphous state may be defined as reset data or data 1. However, noise during write and/or read operations may cause errors in data written to or read from a PRAM cell.
Accordingly, there exists a need to prevent write and/or read data errors from occurring in a nonvolatile memory device.